The use of clamps in well drilling operations are well known. Some examples of this use are guarding against dropping flush joint pipe, streamline drill collars, and similar items into the hole while making up or breaking out the string; as an emergency elevator shoulder for lifting prepacked gravel liners, flush joint pipe, twisted off fish and similar items having no shoulders for attaching conventional elevators; as slip and elevator combinations when running large diameter surface casing; and, then inverted, as a hold down against flotation of surface pipe during cementing operations.
One example of such safety clamp is the--Baash-Ross Safety Clamp, manufactured by Joy Manufacturing Company, designated as type "C safety clamp". This safety clamp comprises individual lengths flexibly hinged to one another to form a linkage mechanism with each length having the separate tapered slip to act as a gripping member. The clamp is tightened by use of a threaded rod extending through a nut, such that each slip can take a firm initial grip on the surface of the pipe. The linkage mechanism is used to that substantial uniform gripping pressure is provided around the pipe which aids in preventing the crushing of thin wall pipe or damaging the pipe's surface. To tighten the clamp on the pipe, a separate wrench is provided. Since the wrench is separate, it may become lost. Further, normally the particular wrench provided is a box-end wrench which does not enable manipulation in relatively tight places. Also, even though a linkage mechanism is used to prevent the crushing of thin wall pipe, normally the particular wrench provided does not have any means of indicating the amount of torque applied to such clamp so as to further aid in preventing the crushing of the thin wall pipe or damaging the pipe's surface.
Accordingly, it is an object of the present invention to provide a safety clamp used on pipe that includes a combined clamp and a wrench portion so as to inhibit the likelihood of loss of a particular portion of the clamp.
Further, it is an object of the present invention to provide a safety clamp used on pipe that includes a ratchet arrangement to facilitate tightening or loosening the clamp in difficult hard to reach areas.
Further, it is an object of the present invention to provide a safety clamp used on a pipe that includes a torque indicator so as to inhibit the likelihood of damage to thin wall pipe or damaging the pipe's surface.
In accordance with the invention, a safety clamp used on pipe comprises a clamp portion for encircling the pipe. The clamp portion includes a body adapter to be positioned around the pipe having first and second ends opposed members for gripping the pipe connected to the body, and a threaded member pivotally connected to the first end of the body for extending through a passageway in a member connected to the second end of the body. A wrench portion for tightening the clamp portion around the pipe includes a nut for moving the threaded member relative thereto and a handle for transferring a torque to the nut. Apparatus connects the nut to the handle and has a ratchet mechanism to transfer the torque from the handle to the nut when the handle is turned in a first direction while permitting movement on the handle in an opposite direction without applying a torque to the nut.
Further in accordance with the invention, a wrench is used to tighten a clamp onto a pipe. The clamp includes a body having first and second ends, opposed members for gripping the pipe connected to the body and a threaded member connected to the first end of the body and extending through a passageway in a member connected to the second end of the body. The wrench comprises a nut adapted to matingly engage the threaded member of the clamp and a handle for applying a torque to the nut. Apparatus connects the nut to the handle and includes a ratchet mechanism for transferring the torque to the nut when the handle is turned in a first direction to move the threaded member relative to the nut to tighten or loosen the clamp on the pipe while permitting movement of the handle in an opposite direction without applying torque to the nut, and a mechanism is connected to the handle for indicating the torque applied to the nut when the handle is moved to transfer torque to the nut.